Reduced area imaging devices incorporated within surgical instruments

ABSTRACT

A reduced area imaging device is provided for use in medical or dental instruments such as an endoscope. In one configuration of the imaging device, the image sensor is placed remote from the remaining circuitry. In another configuration, all of the circuitry to include the image sensor is placed in a stacked fashion at the same location. In a first embodiment of the invention, the entire imaging device can be placed at the distal tip of an endoscope. In a second embodiment, the image sensor is remote from the remaining circuitry according to the first configuration, and wherein a control box can be provided which communicates with the image sensor and is placed remotely from the endoscope. In yet another embodiment, the imaging device can be incorporated in the housing of a standard medical camera which is adapted for use with traditional rod lens endoscopes. In any of the embodiments, the image sensor may be placed alone on a first circuit board, or timing and control circuits may be included on the first circuit board containing the image sensor. One or more video processing boards can be stacked in a longitudinal fashion with respect to the first board, or the video processing boards may be placed in the control box.

TECHNICAL FIELD

This invention relates to surgical instruments that incorporate the useof very small image sensors and associated electronics, and moreparticularly, to surgical instruments such as endoscopes having aninherent imaging capability in the form of complementary metal oxide,semiconductor integrated circuit sensors including active pixel arraysand accompanying processing circuitry.

BACKGROUND ART

In recent years, endoscopic surgery has become the accepted standard forconducting many types of surgical procedures, both in the medical anddental arenas. The availability of imaging devices enabling a surgeon ordentist to view a particular surgical area through a small diameterendoscope which is introduced into small cavities or openings in thebody results in much less patient trauma as well as many otheradvantages.

In many hospitals, the rod lens endoscope is still used in endoscopicsurgery. The rod lens endoscope includes a very precise group of lensesin an elongate and rigid tube which are able to accurately transmit animage to a remote camera in line with the lens group. The rod lensendoscope, because of its cost of manufacture, failure rate, andrequirement to be housed within a rigid and straight housing, is beingincreasingly replaced by solid state imaging technology which enablesthe image sensor to be placed at the distal tip of the investigatingdevice. The three most common solid state image sensors include chargedcoupled devices (CDD), charge injection devices (CID) and photo diodearrays (PDA). In the mid-1980s, complementary metal oxide semiconductors(CMOS) were developed for industrial use. CMOS imaging devices offerimproved functionality and simplified system interfacing. Furthermore,many CMOS imagers can be manufactured at a fraction of the cost of othersolid state imaging technologies.

One particular advance in CMOS technology has been in the activepixel-type CMOS imagers which consist of randomly accessible pixels withan amplifier at each pixel site. One advantage of active pixel-typeimagers is that the amplifier placement results in lower noise levelsthan CCDs or other solid state imagers. Another major advantage is thatthese CMOS imagers can be mass produced on standard semiconductorproduction lines. One particularly notable advance in the area of CMOSimagers including active pixel-type arrays is the CMOS imager describedin U.S. Pat. No. 5,471,515 to Fossum, et al. This CMOS imager canincorporate a number of other different electronic controls that areusually found on multiple circuit boards of much larger size. Forexample, timing circuits, and special functions such as zoom andanti-jitter controls can be placed on the same circuit board containingthe CMOS pixel array without significantly increasing the overall sizeof the host circuit board. Furthermore, this particular CMOS imagerrequires 100 times less power than a CCD-type imager. In short, the CMOSimager disclosed in Fossum, et al. has enabled the development of a"camera on a chip."

Although the camera on a chip concept is one which has great merit forapplication in many industrial areas, a need still exists for a reducedarea imaging device which can be used in even the smallest type ofendoscopic instruments in order to view areas in the body that areparticularly difficult to access, and to further minimize patient traumaby an even smaller diameter invasive instrument.

It is one object of this invention to provide surgical instruments withreduced area imaging devices which take advantage of the CMOS-typeimagers of Fossum, et al., but rearrange the accompanying circuitry in astacked relationship so that there is a minimum profile presented whenused within the surgical instrument. It is another object of thisinvention to provide low cost imaging devices which may be "disposable."It is yet another object of this invention to provide a reduced areaimaging device which may be used in conjunction with standard endoscopesby placing the imaging device through channels which normally receiveother surgical devices, or receive liquids or gases for flushing asurgical area. It is yet another object of this invention to provide asurgical device with inherent imaging capability which may be batterypowered and only requires one conductor for transmitting a pre-videosignal to video processing circuitry within or outside the sterile fieldof the surgical area.

In addition to the intended use of the foregoing invention with respectto surgical procedures conducted by medical doctors, it is alsocontemplated that the invention described herein has great utility withrespect to oral surgery and general dental procedures wherein a verysmall imaging device can be used to provide an image of particularlydifficult to access locations. Additionally, while the foregoinginvention has application with respect to the medical and dental fields,it will also be appreciated by those skilled in the art that the smallsize of the imaging device set forth herein can be applied to otherfunctional disciplines wherein the imaging device can be used to viewdifficult to access locations for industrial equipment and the like.Therefore, the imaging device of this invention could be used to replacemany industrial boroscopes.

The CMOS image sensor technology can be furthered improved with respectto reducing the profile area of the "camera on a chip" and incorporatingsuch a reduced area imaging device into very small investigativeinstruments which can be used in the medical, dental, or industrialfields.

DISCLOSURE OF THE INVENTION

In accordance with the present invention, surgical instrumentsincorporating reduced area imaging devices are provided. The term"imaging device" as used herein describes the imaging elements andprocessing circuitry which is used to produce a video signal which maybe accepted by a standard video device such as a television or videomonitor accompanying a personal computer. The term "image sensor" asused herein describes the CMOS pixel array which captures images andstores them within the structure of each of the pixels in the array.This term also includes the timing and control circuits which enable thestored images to be retrieved from the pixel array. As further discussedbelow, the timing and control circuits can either be placed on the sameplanar substrate as the pixel array and the image sensor can thereforealso be defined as an integrated circuit, or the timing and controlcircuits can be placed remote from the pixel array. The terms "signal"or "image signal" as used herein, and unless otherwise more specificallydefined, refer to an image which at some point during its processing bythe imaging device, is found in the form of electrons which have beenplaced in a specific format or domain. The term "processing circuitry"as used herein refers to the electronic components within the imagingdevice which receive the image signal from the image sensor andultimately place the image signal in a usable format. The terms "timingand control circuits or circuitry" as used herein refer to theelectronic components which control the release of the image signal fromthe pixel array.

In a first embodiment, the image sensor, with or without the timing andcontrol circuitry, may be placed at the distal tip of the endoscopicinstrument while the remaining processing circuitry may be found in asmall remote control box which may communicate with the image sensor bya single cable.

In a second embodiment, the image sensor and the processing circuitrymay all be placed in a stacked arrangement of circuit boards andpositioned at the distal tip of the endoscopic instrument. In thisembodiment, the pixel array of the image sensor may be placed by itselfon its own circuit board while the timing and control circuitry andprocessing circuitry are placed on one or more other circuit boards.Alternatively, the circuitry for timing and control may be placed withthe pixel array on one circuit board, while the remaining processingcircuitry can be placed on one or more of the other circuit boards.

In yet another embodiment, the imaging device may be adapted for usewith a standard rod lens endoscope wherein the imaging device is placedwithin a standard camera housing which is configured to connect to astandard "C" or "V" mount connector.

A generic endoscope may be used in the first and second embodimentswhich includes a very small diameter tubular portion which is insertedwithin the patient. The tubular portion may be made of a flexiblematerial having a central lumen or opening therein for receiving theelements of the imaging device. The tubular portion may be modified toinclude an additional concentric tube placed within the central lumenand which enables a plurality of light fibers to be placedcircumferentially around the periphery of the distal end of the tubularportion. Additionally, control wires may extend along the tubularportion in order to make the endoscope steerable. The material used tomake the endoscope can be compatible with any desired sterilizationprotocol, or the entire endoscope can be made sterile and disposableafter use.

For the configuration of the imaging device which calls for the array ofpixels and the timing and control circuitry to be placed on the samecircuit board, only one conductor is required in order to transmit theimage signal to the processing circuitry. In the other configuration ofthe imaging device wherein the timing and control circuits areincorporated onto other circuit boards, a plurality of connections arerequired in order to connect the timing and control circuitry to thepixel array and the one conductor is also required to transmit the imagesignal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a illustrates a first embodiment including a fragmentarycross-sectional view of a generic endoscopic instrument, and afragmentary perspective view of a control box, the endoscope and controlbox each incorporating elements of a reduced area imaging device;

FIG. 1b is an enlarged fragmentary partially exploded perspective viewof the distal end of the endoscopic instrument specifically illustratingthe arrangement of the image sensor with respect to the other elementsof the tubular portion of the endoscope;

FIG. 2a is a fragmentary cross-sectional view of a second embodiment ofthis invention illustrating another generic endoscope wherein theimaging device is incorporated in its entirety at the distal tip of theendoscope;

FIG. 2b is an enlarged fragmentary partially exploded perspective viewof the distal end of the endoscope of FIG. 2a illustrating the imagingdevice;

FIG. 3a is an elevational fragmentary cross-sectional view of the imagesensor incorporated with a standard camera housing for connection to arod lens endoscope;

FIG. 3b is a fragmentary cross-sectional view of the imaging deviceincorporated within the camera housing of FIG. 3a;

FIG. 3c is a fragmentary cross-sectional view similar to that of FIG. 3billustrating a battery as an alternate source of power;

FIG. 4 is a schematic diagram of the functional electronic componentswhich make up the imaging device;

FIG. 4a is an enlarged schematic diagram of a circuit board which mayinclude the array of pixels and the timing and control circuitry;

FIG. 4b is an enlarged schematic diagram of a video processing boardhaving placed thereon the processing circuitry which processes thepre-video signal generated by the array of pixels and which converts thepre-video signal to a post-video signal which may be accepted by astandard video device; and

FIGS. 5a-5e are schematic diagrams that illustrate an example ofspecific circuitry which may be used to make the imaging device.

BEST MODE FOR CARRYING OUT THE INVENTION

In accordance with one embodiment of the invention as shown in FIG. 1a,an endoscope 10 is provided which incorporates a reduced area imagingdevice 11, shown in FIG. 1b. As further discussed below, the elements ofthe imaging device may all be found at one location or the elements maybe separated from one another and interconnected by the appropriatecable(s). The array of pixels making up the image sensor captures imagesand stores them in the form of electrical energy by conversion of lightphotons to electrons. This conversion takes place by the photo diodes ineach pixel which communicate with one or more capacitors which store theelectrons. The structure of the endoscope 10 includes a flexible orrigid tubular portion 14 which is inserted into the body of the patientand is placed at the appropriate location for viewing a desired surgicalarea. The tubular portion 14 attaches at its proximal end to a handleportion 12 which may be grasped by a surgeon who is conducting theendoscopic procedure. The handle 12 may include a central lumen orchannel 13 which receives therethrough one or more cables or otherstructures which extend to the distal end 16 of tubular portion 14.Handle portion 12 may further include a supplementary channel 15 whichintersects with central channel 13 and which may provide another pointof entry for other cables, fluids or operative instruments to be placedthrough the endoscope.

FIG. 1b illustrates the distal end of the endoscope 16. The distal end16 may be characterized by an outer tube 18 which traverses the lengthof the tubular portion 14 and connects to the handle portion 12. Placedconcentrically within the outer tube 18 may be one or more inner tubes20. In FIG. 1b, the gap between inner tube 20 and outer tube 18 forms aspace in which one or more light fibers 22 or control wires 24 may beplaced. As well understood by those skilled in the art, a plurality ofcircumferentially spaced light fibers as illustrated in FIG. 1b can beused to illuminate the surgical site. Additionally, the control wires 24may communicate with a control mechanism (not shown) integrated on thehandle portion 12 for manipulating the distal end 16 of the endoscope ina desired direction. The flexible tubular portion 14 coupled with asteerable feature enables the endoscope to be placed within windingbodily passages or other locations difficult to reach within the body.

An image sensor 40 may be placed within the central channel defined byinner tube 20. In the configuration shown in FIG. 1b, a cable 26 is usedto house the conductors which communicate with the image sensor 40. Anintermediate support tube 28 may be placed concentrically outside ofcable 26 and concentrically within inner tube 20 to provide thenecessary support for the cable 26 as it traverses through the innerchannel defined by inner tube 20. In lieu of support tube 28, otherwell-known means may be provided to stabilize the cable 26 such as clipsor other fastening means which may attach to the inner concentricsurface of inner tube 20.

A control box 30 may be placed remote from the endoscope 10. The controlbox 30 contains some of the processing circuitry which is used toprocess the image signal produced by image sensor 40. Therefore, theimaging device 11 as previously defined would include the processingcircuitry within control box 30 and the image sensor 40 located at thedistal tip of the endoscope. Control box 30 communicates with imagesensor 40 by means of cable 32 which may simply be an insulated andshielded cable which houses therein cable 26. Cable 32 is stabilizedwith respect to the handle portion 12 by means of a fitting 34 whichensures that cable 32 cannot be inadvertently pushed or pulled withinchannel 13. Additionally, an additional fitting 35 may be provided tostabilize the entry of a light cable 36 which houses the plurality oflight fibers 22.

Image sensor 40 is illustrated as being a planar and square shapedmember. However, the image sensor may be modified to be in a planar andcircular shape to better fit within the channel defined by inner tube20. Accordingly, FIG. 1b further shows an alternate shaped image sensor40' which is round. A lens group or system 42 may be incorporated at thedistal end of the endoscope in order to manipulate the image prior to itbeing impinged upon the array of pixels on the image sensor 40. Thislens system 42 may be sealed at the distal end 16 of the endoscope sothat the tubular portion 14 is impervious to fluids entering through thedistal end 16. In the configuration of the imaging device 11 in FIGS. 1aand 1b, there are only three conductors which are necessary forproviding power to the image sensor 40, and for transmitting an imagefrom the image sensor 40 back to the processing circuitry found withincontrol box 30. Namely, there is a power conductor 44, a groundingconductor 46, and an image signal conductor 48 each of which are hardwired to the image sensor. Thus, cable 26 may simply be athree-conductor 50 ohm cable.

Image sensor 40 can be as small as 1 mm in its largest dimension.However, a more preferable size for most endoscopic procedures woulddictate that the image sensor 40 be between 4 mm to 8 mm in its largestdimension. The image signal transmitted from the image sensor throughconductor 48 is also herein referred to as a pre-video signal. Once thepre-video signal has been transmitted from image sensor 40 by means ofconductor 48, it is received by video processing board 50. Videoprocessing board 50 then carries out all the necessary conditioning ofthe pre-video signal and places it in a form so that it may be vieweddirectly on a standard video device, television or standard computervideo monitor. The signal produced by the video processing board 50 canbe further defined as a post-video signal which can be accepted by astandard video device. As shown in FIG. 1a, a conductor 49 is providedwhich transmits the post-video signal to an output connector 58 on theexterior surface of control box 30. The cable (not shown) extending fromthe desired video device (not shown) may receive the post-video signalby means of connector 58. Power supply board 52 may convert incomingpower received through power source 54 into the desired voltage. In thepreferred CMOS imager incorporated in this invention, the power to theimaging device is simply a direct current which can be a 1.5 volt to a12 volt source. Incoming power from, for example, a wall receptacle,communicates with power supply board 52 by connector 56. Power supplyboard 52 takes the incoming power source and regulates it to the desiredlevel. Additionally, ground 46 is also shown as extending back to thesource of power through connector 56.

FIG. 2a illustrates a second embodiment of this invention wherein theimaging device is self-contained entirely within the distal end 16 ofthe endoscope, and a power source which drives the circuitry within theimaging device may come from a battery 66 housed within handle portion12.

As shown in FIG. 2b, the video processing board 50 may be placeddirectly behind image sensor 40. A plurality of pin connectors 62 serveto electrically couple image sensor 40 with video processing board 50depending upon the specific configuration of image sensor 40, pinconnectors 62 may be provided either for structural support only, or toprovide a means by which image signals are transmitted between imagesensor 40 and board 50. When necessary, one or more supplementary boards60 may be provided which further contain processing circuitry to processthe image signal and present it in a form which may be directly receivedby a desired video device. The area which is occupied by image sensor 40may be defined as the profile area of the imaging device and whichdetermines its critical dimensions. Any imaging elements that are foundon boards 50 or 60 must be able to be placed on one or more circuitboards which are longitudinally aligned with image sensor 40 alonglongitudinal axis XX. If the profile area is not critical in terms oflimiting the largest sized imaging element within the imaging device,then the additional circuit boards 50 and 60 which are normally placedin line with image sensor 40 can be aligned in an offset manner or maybe larger than the profile area of image sensor 40. In the configurationof FIG. 2b, it is desirable that elements 40, 50 and 60 be approximatelythe same size so that they may fit uniformly within the central channelof the endoscope. Additionally, image sensor 40 may be bonded to lenssystem 42 in order to provide further structural support to the imagingdevice 11 when mounted within the distal end 16.

Referring back to the handle portion 12 in FIG. 2a, an additionalchannel 64 may be provided in order that a power supply cable 68 maycommunicate with battery 66. Conveniently, battery 66 may itself bemounted within a well 65 formed in handle portion 12. Cable 68 carriesthe conductor 44 and ground 46. Cable 68 may intersect with cable 33within channel 13, cables 68 and 33 extending then to the distal end 16.Cable 33 can be a single conductor cable which transmits the post-videosignal to a desired video device. In other words, cable 33 may simply bean insulated and shielded housing for conductor 49 which carries thepost-video signal. Because the preferred CMOS image sensor of theimaging device 11 only requires a 5 volt power supply, a battery is anideal power source in lieu of a conductor which would trail theendoscope. Accordingly, the endoscope is made more mobile and easier tohandle by eliminating at least one of the trailing cables.

FIG. 3a illustrates yet another preferred embodiment of this invention,wherein the imaging device can be used in conjunction with a standardrod lens endoscope 70. As shown, rod lens endoscope 70 includes a lenstrain 72 which includes a plurality of highly precise lenses (not shown)which are able to transmit an image from the distal end of theendoscope, to a camera in line with the endoscope. The rod lensendoscope is equipped with a light guide coupling post 74. Light guidepost 74 connects to a source of light in the form of a cable 77 having aplurality of fiber optic strands (not shown) which communicate with asource of light (not shown). The most common arrangement of the rod lensendoscope also includes a "C" or "V" mount connector 78 which attachesto the eyepiece 76. The "C" or "V" mount attaches at its other end to acamera group 80. The camera group 80 houses one or more of the elementsof the imaging device. In this embodiment, the small size of the imagingdevice is not a critical concern since the imaging device is not beingplaced at the distal end of the endoscope. However, the incorporation ofthe imaging device in a housing which would normally hold a traditionalcamera still provides an advantageous arrangement. As shown, the cameragroup 80 may include a housing 82 which connects to a power/video cable86. Fitting 87 is provided to couple cable 86 to the interior elementsof the camera group 80 found within housing 82. FIG. 3a illustrates anarrangement of the imaging device 11 wherein the image sensor 40 isplaced by itself within the housing 82 and the processing circuitry ofthe imaging device can be positioned in a remote control box as shown inFIG. 1a. Accordingly, only three conductors 44, 46 and 48 are necessaryfor providing power to the image sensor 40 and for transmitting thepre-video signal to the control box. Alternatively, as shown in FIG. 3b,the entire imaging device 11 may be incorporated within camera group 80,each of the elements of the imaging device being placed in the stackedarrangement similar to FIG. 2b. As discussed above, size is not as muchof a concern in the embodiment of FIG. 3a and 3b since the camera grouphousing 82 is much larger than the distal tip of the endoscope of FIGS.1a and 2a.

FIG. 3c also illustrates the use of a battery 66 which provides sourceof power to the imaging device in either FIG. 3a or 3b. In thisarrangement, housing 82 is altered to include a battery housing 69 whichhouses the battery 66 therein. Battery housing 69 may include a verysmall diameter channel which may allow conductor 48 or 49 to communicatedirectly with the processing circuitry or video device, respectively. Itwill also be understood that the embodiment in FIG. 1a may incorporatethe use of a battery 66 as the source of power. Thus, handle 12 in FIG.1a may be altered in the same way as housing 82 to allow a battery to beattached to the handle portion 12.

FIG. 4 is a schematic diagram illustrating one way in which the imagingdevice 11 may be constructed. As illustrated, the CMOS image sensor 40may include the timing and control circuits on the same planarstructure. Power is supplied to image sensor 40 by power supply board52. The connection between image sensor 40 and board 52 may simply be acable having two conductors therein, one for ground and another fortransmitting the desired voltage. These are illustrated as conductors 44and 46. The output from image sensor 40 in the form of the pre-videosignal is input to video processor board 50 by means of the conductor48. In the configuration of FIG. 4, conductor 48 may simply be a 50 ohmconductor. Power and ground also are supplied to video processing board50 by conductors 44 and 46 from power supply board 52. The output signalfrom the video processor board 50 is in the form of the post-videosignal and which may be carried by conductor 49 which can also be a 50ohm conductor.

In the first embodiment illustrated in FIG. 1a, cable 32 can be used tohouse conductors 44, 46 and 48. In the embodiment shown in FIG. 2a,cable 33 can be used to house conductor 49 by itself when a batterypower source is used, or alternatively, cable 33 may house conductors44, 46 and 49 if the embodiment of FIG. 2a utilizes a power source fromboard 52.

Optionally, a supplementary processing board 60 may be provided tofurther enhance the pre-video signal. As shown in FIG. 4, thesupplementary board 60 may be placed such that the pre-video signal fromimage sensor 40 is first sent to the supplementary board and then outputto the video processor board 50. In this case, the output from board 50can be carried along conductor 51. This output can be defined as anenhanced pre-video signal. Furthermore, the post-video signal from videoprocessor board 50 may return to the supplementary board 60 for furtherprocessing, as further discussed below. The conductor used to transmitthe post-video signal back to the supplementary board is shown asconductor 59. The power supply board 52 may also provide power to thesupplementary board in the same manner as to image sensor 40 and board50. That is, a simple hard-wired connection is made onto thesupplementary board for the ground and voltage carrying conductors. Asdiscussed above, image sensor 40 may be placed remotely from boards 50and 60. Alternatively, image sensor 40, and boards 50 and 60 each may beplaced within the distal end of the endoscope.

Although FIG. 4 illustrates the CMOS image sensor and the timing andcontrol circuits being placed on the same planar structure, it ispossible to separate the timing and control circuits from the pixelarray and place the timing and control circuits onto video processingboard 50. The advantage in placing the timing and control circuits onthe same planar structure as the image sensor is that only threeconnections are required between image sensor 40 and the rest of theimaging device, namely, conductors 44, 46 and 48. Additionally, placingthe timing and control circuits on the same planar structure with thepixel array results in the pre-video signal having less noise.Furthermore, the addition of the timing and control circuits to the sameplanar structure carrying the image sensor only adds approximately 0.25millimeters to one dimension of the planar structure. If the pixel arrayis to be the only element on planar structure, then additionalconnections must be made between it and the video processing board 50 inorder to transmit the clock signals and other control signals to thepixel array. For example, a ribbon-type cable (not shown) or a pluralityof 50 ohm coaxial cables (not shown) must be used in order to controlthe downloading of information from the pixel array. Each of theseadditional connections would be hard wired between the boards.

FIG. 4a is a more detailed schematic diagram of image sensor 40 whichcontains an array of pixels 90 and the timing and control circuits 92.The preferred CMOS pixel array 90 is similar to that as disclosed inU.S. Pat. No. 5,471,515 to Fossum, et al., said patent beingincorporated in its entirety by reference. More specifically, FIG. 3 ofFossum, et al. illustrates the circuitry which makes up each pixel inthe array of pixels 90. The array of pixels 90 as described in Fossum,et al. is an active pixel group with intra-pixel charged transfer. Theimage sensor made by the array of pixels is formed as a monolithiccomplementary metal oxide semiconductor integrated circuit which may bemanufactured in an industry standard complementary metal oxidesemiconductor process. The integrated circuit includes a focal planearray of pixel cells, each one of the cells including a photo gateoverlying the substrate for accumulating the photo generated charges. Inbroader terms, as well understood by those skilled in the art, an imageimpinges upon the array of pixels, the image being in the form ofphotons which strike the photo diodes in the array of pixels. The photodiodes or photo detectors convert the photons into electrical energy orelectrons which are stored in capacitors found in each pixel circuit.Each pixel circuit has its own amplifier which is controlled by thetiming and control circuitry discussed below. The information orelectrons stored in the capacitors is unloaded in the desired sequenceand at a desired frequency, and then sent to the video processing board50 for further processing.

The timing and control circuits 92 are used to control the release ofthe image information or image signal stored in the pixel array. In thepreferred image sensor of Fossum, et al., the pixels are arranged in aplurality of rows and columns. The image information from each of thepixels is first consolidated in a row by row fashion, and is thendownloaded from one or more columns which contain the consolidatedinformation from the rows. As shown in FIG. 4a, the control ofinformation consolidated from the rows is achieved by latches 94,counter 96, and decoder 98. The operation of the latches, counter anddecoder is similar to the operation of similar control circuitry foundin other imaging devices. That is, a latch is a means of controlling theflow of electrons from each individual addressed pixel in the array ofpixels. When a latch 94 is enabled, it will allow the transfer ofelectrons to the decoder 98. The counter 96 is programmed to count adiscrete amount of information based upon a clock input from the timingand control circuits 92. When the counter 96 has reached its set pointor overflows, the image information is allowed to pass through thelatches 94 and be sent to the decoder 98 which places the consolidatedinformation in a serial format. Once the decoder 98 has decoded theinformation and placed it in the serial format, then the row driver 100accounts for the serial information from each row and enables each rowto be downloaded by the column or columns. In short, the latches 94 willinitially allow the information stored in each pixel to be accessed. Thecounter 96 then controls the amount of information flow based upon adesired time sequence. Once the counter has reached its set point, thedecoder 98 then knows to take the information and place it in the serialformat. The whole process is repeated, based upon the timing sequencethat is programmed. When the row driver 100 has accounted for each ofthe rows, the row driver reads out each of the rows at the desired videorate.

The information released from the column or columns is also controlledby a series of latches 102, a counter 104 and a decoder 106. As with theinformation from the rows, the column information is also placed in aserial format which may then be sent to the video processing board 50.This serial format of column information is the pre-video signal carriedby conductor 48. The column signal conditioner 108 places the columnserial information in a manageable format in the form of desired voltagelevels. In other words, the column signal conditioner 108 only acceptsdesired voltages from the downloaded column(s).

The clock input to the timing and control circuits 92 may simply be aquartz crystal timer. This clock input is divided into many otherfrequencies for use by the various counters. The run input to the timingand control circuit 92 may simply be an on/off control. The defaultinput can allow one to input the pre-video signal to a video processorboard which may run at a frequency of other than 30 hertz. The datainput controls functions such as zoom. Since the CMOS active pixel arraycan be accessed in a random manner, features such as zoom are easilymanipulated by addressing only those pixels which locate a desired areaof interest by the surgeon.

A further discussion of the timing and control circuitry found on board40 and incorporated with the pixel array 90 is described in an articleentitled "Active Pixel Image Sensor Integrated With Readout Circuits"appearing in NASA Tech Briefs, pp. 38 and 39 of the October, 1996publication. The disclosure of this particular article is alsoincorporated by reference herein.

Once image sensor 40 has created the pre-video signal, it is sent to thevideo processing board 50 for further processing. At board 50, as shownin FIG. 4b, the pre-video signal is passed through a series of filters.One common filter arrangement may include two low pass filters 114 and116, and a band pass filter 112. The band pass filter only passes lowfrequency components of the signal. Once these low frequency componentspass, they are then sent to detector 120 and white balance circuit 124,the white balance circuit distinguishing between the colors of red andblue. The white balance circuit helps the imaging device set its normal,which is white. The portion of the signal passing through low passfilter 114 then travels through gain control 118 which reduces themagnitude or amplitude of this portion to a manageable level. The outputfrom gain control 118 is then fed back to the white balance circuit 124.The portion of the signal traveling through filter 116 is placed throughthe processor 122. In the processor 122, the portion of the signalcarrying the luminance or non-chroma is separated and sent to the Ychroma mixer 132. Any chroma portion of the signal is held in processor122.

Referring to the output of the white balance circuit 124, this chromaportion of the signal is sent to a delay line 126 where the signal isthen further reduced by switch 128. The output of switch 128 is sentthrough a balanced modulator 130 and also to the Y chroma mixer 132where the processed chroma portion of the signal is mixed with theprocessed nonchroma portion. Finally, the output from the Y chroma mixer132 is sent to the NTSC/PAL encoder 134, commonly known in the art as a"composite" encoder. The composite frequencies are added to the signalleaving the Y chroma mixer 132 in encoder 134 to produce the post-videosignal which may be accepted by a television.

Referring back to FIG. 4, it further illustrates supplementary board 60which may be used to digitally enhance or otherwise further conditionthe pre-video signal produced from image sensor 40. For example, digitalenhancement can brighten or otherwise clarify the edges of an imageviewed on a video screen. Additionally, the background images may beremoved thus leaving only the foreground images or vice versa. Theconnection between image sensor 40 and board 60 may simply be theconductor 48 which may also transfer the pre-video signal to board 50.Once the pre-video signal has been digitally enhanced on supplementaryboard 60, it is then sent to the video processor board 50 by means ofanother conductor 51. The pre-video signal is an analog signal. Thedigitally enhanced pre-video signal may either be a digital signal or itmay be converted back to the analog domain prior to being sent to board50.

In addition to digital enhancement, supplementary board 60 may furtherinclude other circuitry which may further condition the post-videosignal so that it may be viewed in a desired format other than NTSC/PAL.As shown in FIGS. 4, intermediate conductor 59 may transmit the signaloutput from Y chroma mixer 132 back to the supplementary board 60 wherethe signal is further encoded for viewing in a particular format. Onecommon encoder which can be used includes an RGB encoder 154. The RGBencoder separates the signal into three separate colors (red, green andblue) so that the surgeon may selectively choose to view only thoseimages containing one or more of the colors. Particularly in tissueanalysis where dyes are used to color the tissue, the RGB encoder mayhelp the surgeon to identify targeted tissue.

The next encoder illustrated in FIG. 4 is a SVHS encoder 156 (supervideo home system). This encoder splits or separates the luminanceportion of the signal and the chroma portion of the signal prior toentering the video device. Some observers believe that a cleaner signalis input to the video device by such a separation which in turn resultsin a more clear video image viewed on the video device. The last encoderillustrated in FIG. 4 is a VGA encoder 158 which enables the signal tobe viewed on a standard VGA monitor which is common to many computermonitors.

One difference between the arrangement of image sensor 40 and theoutputs found in FIG. 3 of the Fossum, et al. patent is that in lieu ofproviding two analog outputs namely, VS out (signal) and VR out(reset)!, the reset function takes place in the timing and controlcircuitry 92. Accordingly, the pre-video signal only requires oneconductor 48.

FIGS. 5a-5e illustrate in more detail one example of circuitry which maybe used in the video processing board 50 in order to produce apost-video signal which may be directly accepted by a video device suchas a television. The circuitry disclosed in FIGS. 5a-5e is very similarto circuitry which is found in a miniature quarter-inch Panasoniccamera, Model KS-162. It will be understood by those skilled in the artthat the particular arrangement of elements found in FIGS. 5a-5e areonly exemplary of the type of video processing circuitry which may beincorporated in order to take the pre-video signal and condition it tobe received by a desired video device.

As shown in FIG. 5a, 5 volt power is provided along with a ground byconductors 44 and 46 to board 50. The pre-video signal carried byconductor 48 is buffered at buffer 137 and then is transferred toamplifying group 138. Amplifying group 138 amplifies the signal to ausable level as well as achieving impedance matching for the remainingcircuitry.

The next major element is the automatic gain control 140 shown in FIG.5b. Automatic gain control 140 automatically controls the signal fromamplifying group 138 to an acceptable level and also adds othercharacteristics to the signal as discussed below. More specifically,automatic gain control 140 conditions the signal based upon inputs froma 12 channel digital to analog converter 141. Converter 141 retrievesstored information from EEPROM (electrically erasable programmable readonly memory) 143. EEPROM 143 is a non-volatile memory element which maystore user information, for example, settings for color, tint, balanceand the like. Thus, automatic gain control 140 changes the texture orvisual characteristics based upon user inputs. The signal leaving theautomatic gain control 140 is an analog signal until being converted byanalog to digital converter 142.

Digital signal processor 144 of FIG. 5c further processes the convertedsignal into a serial type digital signal. One function of themicroprocessor 146 is to control the manner in which digital signalprocessor 144 sorts the digital signals emanating from converter 142.Microprocessor 146 also controls analog to digital converter 142 interms of when it is activated, when it accepts data, when to releasedata, and the rate at which data should be released. Microprocessor 146may also control other functions of the imaging device such as whitebalance. The microprocessor 146 may selectively receive the informationstored in the EEPROM 143 and carry out its various commands to furthercontrol the other elements within the circuitry.

After the signal is processed by digital signal processor 144, thesignal is sent to digital encoder 148 illustrated in FIG. 5d. Some ofthe more important functions of digital encoder 148 are to encode thedigital signal with synchronization, modulated chroma, blanking,horizontal drive, and the other components necessary so that the signalmay be placed in a condition for reception by a video device such as atelevision monitor. As also illustrated in FIG. 5d, once the signal haspassed through digital encoder 148, the signal is reconverted into ananalog signal through digital to analog converter 150.

This reconverted analog signal is then buffered at buffers 151 and thensent to amplifier group 152 of FIG. 5e which amplifies the signal sothat it is readily accepted by a desired video device. Specifically, asshown in FIG. 5e, one SVHS outlet is provided at 160, and two compositeor NTSC outlets are provided at 162 and 164, respectively.

From the foregoing, it is apparent that an entire imaging device may beincorporated within the distal tip of an endoscope, or may have someelements of the imaging device being placed in a small remote boxadjacent to the endoscope. Because of the particular type of CMOS imagesensor used, the profile area of the imaging device is small enough tobe placed into an endoscope which has a very small diameter tube.Additionally, the imaging device may be placed into the channels ofexisting endoscopes to provide additional imaging capability withoutincreasing the size of the endoscope. The imaging device may be poweredby a standard power input connection in the form of a power cord, or asmall lithium battery may be used.

This invention has been described in detail with reference to particularembodiments thereof, but it will be understood that various othermodifications can be effected within the spirit and scope of thisinvention.

What is claimed is:
 1. A reduced area imaging device comprising:a firstcircuit board defining a profile area and lying in a first plane, saidfirst circuit board including an array of CMOS pixels on said firstplane for receiving images thereon and wherein individual CMOS pixelswithin said array of CMOS pixels each include an amplifier, said firstcircuit board further including circuitry means on said first plane andcoupled to said array of CMOS pixels for timing and control of saidarray of CMOS pixels, said first circuit board producing an analogpre-video signal; a pre-video conductor for transmitting said pre-videosignal, said conductor having first and second ends, said first endconnected to said first circuit board; a second circuit board lying in asecond plane and longitudinally aligned with said first circuit board,said second circuit board being connected to said conductor at saidsecond end thereof, said second circuit board including circuitry meansfor converting said pre-video signal to a post-video signal forreception by a standard video device; and a power supply electricallycoupled with said first circuit board for driving said array of CMOSpixels, and said timing and control means, and electrically coupled tosaid second circuit board for driving said second circuit board.
 2. Areduced area imaging device, as claimed in claim 1, further including:asupplementary circuit board electrically coupled with said first andsecond circuit boards for enhancing said pre-video signal prior toreception by said second circuit board, said supplementary circuit boardbeing longitudinally aligned with said first and second circuit boardsand being positioned so as not to substantially extend beyond saidprofile area.
 3. A reduced imaging device comprising:an array of CMOSpixels defining a profile area and lying in a first plane, said array ofCMOS pixels for receiving images thereon; a circuit board longitudinallyaligned with and electrically coupled to said array of CMOS pixels, saidcircuit board lying in a second plane which is offset from said firstplane and substantially parallel to said first plane, said circuit boardincluding circuitry means for timing and control of said array of CMOSpixels, said timing and control means producing an analog pre-videosignal, said circuit board further including circuitry means forreceiving said analog pre-video signal from said timing and controlmeans and converting said pre-video signal to a post-video output signalfor reception by a video device; and a power supply electrically coupledto said array of CMOS pixels, and said circuit board.
 4. A device, asclaimed in claim 3, further including:a supplementary circuit boardcommunicating with said array of CMOS pixels and said circuit board forenhancing said analog pre-video signal, said supplementary circuit boardbeing longitudinally aligned with said array of CMOS pixels and saidcircuit board and being positioned so as not extend substantially beyondsaid profile area.
 5. An endoscope with integral imaging capabilitycomprising:a tubular portion including a distal end, a proximal end anda central passageway extending therethrough; a handle connected to saidproximal end of said tubular portion for grasping by a surgeon; at leastone light fiber positioned around a periphery of said distal end forilluminating a surgical site; a CMOS image sensor lying in a first planeand positioned at said distal end of said tubular portion for receivingimages of the surgical site, said CMOS image sensor defining a profilearea, and said CMOS image sensor producing an image signal; circuitrymeans electrically coupled to said CMOS image sensor for timing andcontrol of said CMOS image sensor, said circuitry means for timing andcontrol placed within said tubular portion; a video processor boardspaced from and longitudinally aligned with said CMOS image sensorwithin said tubular portion and adjacent said distal end thereof, saidvideo processor board lying in a second plane, said video processorboard including circuitry means for processing said image signal andconverting said image signal to a post-video signal, said videoprocessor board being positioned so as not to extend substantiallybeyond said profile area; a conductor connected between said CMOS imagesensor and said video processor board for transmitting said image signalto said video processor board; and a power supply electrically coupledto said CMOS image sensor and said video processor board.
 6. Anendoscope, as claimed in claim 5, wherein:said conductor includes asingle conducting element.
 7. An endoscope, as claimed in claim 5,wherein:said timing and control means is placed adjacent said imagesensor and on said first plane with said image sensor; andwherein saidimage signal is a pre-video signal.
 8. An endoscope, as claimed in claim5, wherein:said timing and control means is placed on said second planewith said video processor board.
 9. An endoscope, as claimed in claim 5,wherein:said power supply is a battery attached to said handle.
 10. Adevice, as claimed in claim 1, wherein:said first plane is offset fromand substantially parallel to said second plane.
 11. A device, asclaimed in claim 1, wherein:said second circuit board is positioned soas not to extend substantially beyond said profile area of said firstcircuit board.
 12. A device, as claimed in claim 1, wherein:said meansfor converting said pre-video signal to a post-video signal is locatedon said second plane of said second circuit board.
 13. An endoscope, asclaimed in claim 5, further including:a lens positioned at said distalend of said tubular portion and distally of said CMOS image sensor forproducing a modified image on said CMOS image sensor.
 14. An endoscope,as claimed in claim 5, wherein:said CMOS image sensor lies in a firstplane, and said video processor board lies in a second plane offset fromand substantially parallel to said first plane.
 15. An endoscope, asclaimed in claim 5, wherein:said video processor board is positioned inlongitudinal alignment with said CMOS image sensor so that said videoprocessor board does not extend substantially beyond said profile area.